1. Field of the Invention
The present invention relates to a PT (push-to) service, and more particularly, to a mobile terminal, system and method for changing a duration of a talk burst control timer.
2. Description of the Related Art
A PT service is intended to provide rapid communications for business and consumers of mobile networks. The PT service can be a push to talk over cellular (PoC) for providing a call service by sending voice data, a push to view (PTV) for sending moving picture (video) data, or a communication service such as a push to data (PTD) for sending data. In a PT service system, a PT client (e.g., a client supporting a PT service) that wishes to transmit media data (voice, video, data, etc.) needs to first have an authority/permission to transmit the media data. Thus, prior to the actual transmission of the media data (talk burst), the PT client that wishes to transmit the media data transmits a request for a talk burst (a talk burst request message) to an associated PT server. Once the PT client receives the permission, then the PT client sends media data to one or more other PT clients with which a session has been established. The PT service allows user voice, moving picture and data communications to be shared with a single recipient (1-to-1) or between groups of recipients as in a group chat session (1-to-many), and uses a session initiation protocol (SIP) to establish a session.
Generally, the PT service system comprises a PT client for calling a PT service, and a PT server for sending voice, video and data between PT clients and controlling the transmission of talk bursts by using a talk burst control protocol (TBCP) so as to implement each type of PT services.
The PT client comprises at least one talk burst control timer for measuring a time duration after sending a talk burst control protocol (TBCP) message to the PT server, or receiving a TBCP message from the PT server, or performing a specific command. Each talk burst control timer has a specific duration (time) value set and fixed at the time of fabricating the PT service system or at the time of an initial operation, and the set time values of the talk but control timers are not varied thereafter according to the related art.
For example, a talk burst request timer (talk burst control timer) is started when a PT client sends a talk burst request message to its PT server. When the PT client receives a response to the talk burst request message from the PT server within the set time (duration) of the talk burst request timer, the talk burst request timer completes its operation. If the PT client does not receive a response to the talk burst request message from the PT server within the set time of the talk burst request timer, the PT client re-sends a talk burst request message and the talk burst request timer is initialized and started again at that time.
Since the set time value of such a talk burst control timer controls how long a PT client should wait before the PT client re-sends the talk burst request message, the set time value of the talk burst control timer greatly influences a quality of experience (QoE) that a PT service user feels, and a load of a network including the PT server which may increase or decrease according to the set time value of the talk burst control timer. For instance, more frequent retransmission of talk burst request messages will occur if the set time value of the talk burst request timer is small, which will increase network traffic and load.
A problem with such talk burst control timer of the related art is that it is operated with the fixedly set time value, always and without consideration of a network environment change. The talk burst control timer and the PT system according to the related art are not configured to consider and accommodate a current load circumstance of the network and thus the QoE is decreased. For instance, even if a current network condition requires minimum network load, a PT client resends the talk burst request message frequently according to the set time value of the talk burst control timer, which results in the decrease of QoE and worsens the network load condition.
Therefore, there is a need for a technique to change a time duration of a talk burst control timer, i.e., the value of the talk burst control timer. There is another need for a manager or a PT server to be able to change the value of the talk burst control timer with consideration of network environment. A procedure or a basis for changing the value of the talk burst control timer into an optimized value desired by the manager or the PT server is not provided in the related art.